CVE-2015-0565 in DRAM
Summary
by MITRE
NaCl in 2015 allowed the CLFLUSH instruction, making rowhammer attacks possible.
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Analysis
by VulDB Data Team • 08/25/2025
The vulnerability identified as CVE-2015-0565 represents a critical security flaw in Google's Native Client (NaCl) technology that was prevalent in 2015. This issue emerged within the sandboxing mechanism designed to provide secure execution environments for untrusted code, specifically affecting the memory management capabilities of the NaCl runtime. The vulnerability stems from the improper restriction of privileged instructions, allowing malicious code within the NaCl sandbox to execute the CLFLUSH instruction which should normally be restricted to kernel-level operations.
The technical flaw manifests through the unauthorized execution of the CLFLUSH instruction within the NaCl environment, which enables attackers to flush cache lines from memory. This capability directly enables rowhammer attacks by allowing malicious code to repeatedly access specific memory addresses, causing bit flips in adjacent memory locations through the physical phenomenon of rowhammer. The vulnerability exists because the NaCl implementation failed to properly validate or restrict execution of this privileged instruction, creating a pathway for attackers to bypass the intended security boundaries of the sandboxed environment. This flaw operates at the intersection of hardware-level memory behavior and software-level privilege management, creating a dangerous convergence that undermines the fundamental security assumptions of the sandboxing architecture.
The operational impact of CVE-2015-0565 is substantial, as it effectively removes a critical security boundary that was designed to prevent malicious code from accessing low-level hardware functions. Rowhammer attacks enabled through this vulnerability can lead to privilege escalation, data corruption, and potential system compromise by exploiting the physical properties of DRAM memory cells. The vulnerability affects systems running affected versions of Chrome and other applications that utilize NaCl technology, potentially exposing users to sophisticated attacks that can bypass traditional security measures. This weakness particularly impacts enterprise environments where NaCl is used for executing untrusted code, as it provides attackers with a method to escalate privileges and gain unauthorized access to system resources. The vulnerability operates within the ATT&CK framework under the technique of privilege escalation through hardware manipulation, specifically leveraging the rowhammer attack pattern that targets memory architecture weaknesses.
Mitigation strategies for CVE-2015-0565 primarily involve updating to patched versions of affected software that properly restrict the execution of CLFLUSH instructions within NaCl environments. Organizations should implement comprehensive patch management programs to ensure all systems utilizing NaCl technology are updated to versions that address this privilege escalation vulnerability. Additionally, system administrators should consider disabling NaCl functionality where possible, particularly in environments where it is not required for legitimate business operations. The remediation approach aligns with CWE-254 standards for privilege management, emphasizing the importance of proper instruction set restrictions and access controls. Security monitoring should be enhanced to detect anomalous memory access patterns that might indicate attempted rowhammer exploitation, while hardware-level mitigations such as memory error correction and updated DRAM technologies should be considered to address the underlying physical vulnerability that enables these attacks.